1. Field of the Invention
This invention relates to internal combustion engines, and particularly to exhaust systems for outboard motor internal combustion engines.
2. Description of the Prior Art
A typical outboard motor exhaust gas system includes an exhaust conduit structure which communicates with all of the exhaust ports and discharges the exhaust gases from the exhaust ports into the driveshaft housing. The exhaust gases travel through the driveshaft housing and exit through the propeller.
Exhaust relief systems have also been provided for venting the exhaust gases through a discharge outlet located above the water when the engine is operating at relatively low speeds.
Attention is directed to the following United States Patents:
______________________________________ U.S. Pat. No. Inventor Issued ______________________________________ 3,020,707 Post et al. February 13, 1962 3,692,006 Miller et al. September 19, 1972 3,969,893 Sakurai et al. July 20, 1976 3,994,129 Sakurai et al. November 30, 1976 4,034,561 Sakurai et al. July 12, 1977 4,092,958 Hale June 6, 1978 4,165,720 Barcak August 28, 1979 4,184,462 Hale January 22, 1980 4,187,809 Lanpheer et al. February 12, 1980 4,381,644 Kusche May 3, 1983 4,484,442 Hale November 27, 1984 4,559,908 Flaig et al. December 24, 1985 4,702,202 Hensel et al. October 27, 1987 4,799,905 Broughton et al. January 24, 1989 4,906,214 Towner March 6, 1990 4,940,435 Osborn et al. July 10, 1990 4,955,838 Wenstadt September 11, 1990 ______________________________________